ECG Review

When Did the Chest Pain Begin?

By Ken Grauer, MD, Professor, Assistant Director, Family Practice Residency Program, University of Florida. Dr. Grauer reports no financial relationship to this field of study.

Figure. 12-lead ECG recorded from a 50-year-old man with severe chest pain 5 days earlier, but whose symptoms resolved 2-3 days before this ECG was obtained.

Clinical Scenario: The ECG in the Figure was obtained from a 50-year-old man who presented to the office for evaluation of chest pain. His symptoms began 5 days before the ECG shown here was recorded. The patient’s chest pain was initially severe, and had lasted about 2 days—but then resolved. He has several cardiac risk factors, but no prior history of coronary artery disease. In view of this information, how would you interpret his ECG? No prior tracing is available.

Interpretation/Answer: Although P waves are of small amplitude, the rhythm is sinus at a rate of 65/minute. All intervals and the mean QRS axis are normal. There is no ECG evidence of chamber enlargement. There are small q waves in virtually all of the lateral leads. The most remarkable finding on the tracing is slight but definite ST segment elevation in the precordial leads.

ST segment deviations (elevation or depression) are judged with respect to the preceding PR segment. A small amount of ST segment elevation with an upward concavity (ie, "smiley" configuration) is commonly seen as a normal finding in one or more precordial leads, especially V2 through V4. The normal variant pattern known as "early repolarization" often produces J-point ST segment elevation in inferior or lateral leads. The problem arises when an adult of suitable age with cardiac risk factors presents with chest pain but without availability of a prior tracing for comparison. This is the situation here.

We suspect that the ECG in this case is benign. The lateral q waves in leads I, aVL, V5 and V6 are probably normal septal q waves. Although impossible to rule out recent MI (myocardial infarction) without a prior tracing for comparison, the shape of the ST segments, the diffuse nature of the changes seen here in multiple leads, and the lack of reciprocal ST segment depression make recent infarction unlikely. If an acute MI had occurred 5 days ago, one would have expected evolutionary changes to occur by now (ie, deepening Q waves, ST segment coving, and T wave inversion).